The tinkle of distant dropped cutlery echoes around an expanse of brick and glass. We are eating in the Booking Office. Yes – the old booking hall of St Pancras station, now reconfigured as hotel restaurant and cocktail bar.

More than £150m has been spent reinventing the ticket office as bar, forecourt as lofty reception (currently filled with clouds of cherry blossom) and, most importantly, breathing new life into England's finest railway hotel.

As a student, I remember passing the former Midland Grand, its pointy towers and arched windows part fairytale, part schlock-horror set. A collision of fantasy and function on the Euston Road. The hotel closed almost 80 years ago and decades later only narrowly avoided demolition.

Thank God it's still here, Tania and I agree, settling back against black leather, as self-satisfied as cigar-puffing grandees in a gentlemen's club. The Hogwartsian space is cleverly divided and lit just right, so we are aware only of the undulating beauty of oak linenfold panelling and heavy glass lamps in our own "bit", not overwhelmed by the soaring gothic windows, or the sheer distance from the far end of the room.

"You can have a glass of Bolly for £13," says Tania. "And that's a good white." She points at La Croix Vermentino sauvignon blanc, £5.25 a glass. "Pity they only have whites from Castello Banfi, though."

Then, "Proper peasanty," she says, scooping coarse duck terrine on to sourdough toast while I spoon up pea and ham soup. We follow with roast fillet of seabass and a little fricassee of peppers and mushrooms. "Simple, subtle, but delicious," she says.

The public areas of Sir George Gilbert Scott's Victorian masterpiece are simply mesmerising. The stone cantilevered staircase, curved hallways of Minton tiles and unexpectedly decorative, jewel-coloured pattern and illustration on walls, cornices and ceilings all carefully, lovingly restored.

There are 38 suites in the original building and a further 207 rooms in a new annexe, Barlow House. Those rooms are not a bad size, if unexciting (and I'd advise an upper floor). At this scale, though, it is impossible to avoid creeping corporateness – even in the suites. Mine is comfortable for sure, with a marble bathroom (REN products in a glass-lidded box), office area, heavy sunburst mirror, easy chairs positioned for gazing across the giant Olympic symbol to Platform 9 and Eurostar. Wi-Fi is free (but only in the suites) and marks for not being too snobbish to provide tea- and coffee-making things, too. Just because I have the services of a butler doesn't mean I want to rack up room service bills.

I am less keen on being woken at 7am by a platform announcement (not sure it would be any quieter facing Euston Road – especially as double glazing isn't allowed for the listed windows) but, hey, it's fun watching everyone scurrying about below. Even though, since my stay, Marcus Wareing has opened his Gilbert Scott Brasserie, designed by David Collins, in the former hotel entrance hall and coffee room, and stolen all the thunder, I urge you to make time for coffee, if nothing else, in the Booking Office. It is surely the most inspiring new public space in London.